Method for supplying molten metal, system for supplying molten metal, producing method for producing aluminum, producing method for producing aluminum molding product, producing method of automobile, transporting vehicle, container, and apparatus for supplying molten metal

ABSTRACT

The present invention comprises a sealed type container body ( 50 ) capable of storing molten metal; a flow passage ( 57 ) capable of flowing the molten metal, the passage is formed extended to an outside of the container, and the passage is formed towards an upper portion ( 57   b ) from an opening ( 57   a ) provided at a position on an inner and near a bottom portion ( 50   a ) of the container body ( 50 ); and means ( 101, 0313 ) for controlling the pressure in the container body. This makes it possible to provide a container or the like requiring no replacement of parts such as a stoke and the like.

TECHNICAL FIELD

The present invention relates to a method for supplying a molten metalused for carrying, for example, molten aluminum, a system for supplyinga molten metal, a producing method for producing a molten aluminum, aproducing method for producing an aluminum molding product, a producingmethod of an automobile, a transporting vehicle, a container, and anapparatus for supplying a molten metal.

BACKGROUND ART

In a factory where aluminum is molded using many die-casting machines,an aluminum material is often supplied not only from within the factorybut also from outside the factory. In this case, a container storingaluminum in a melt is carried from a factory on the material supply sideto a factory on the molding side to supply to each of the die-castingmachines the material kept in the melt.

DISCLOSURE OF THE INVENTION

The present inventors propose a technique of supplying the moldingmaterial from such a container to the die-casting machine side utilizinga pressure difference. More specifically, this technique applies apressure to the container to pour a molten material in the container tothe outside through a pipe led to the container. As such a container, itis possible to use, for example, an apparatus disclosed in JapanesePatent Laid-Open No. Hei 8-20826.

The apparatus disclosed in Japanese Patent Laid-Open No. Hei 8-20826,however, has a problem that since its stoke is kept exposed to themolten metal in the container, there often occurs a necessity to replacethe oxidized and corroded stoke. Besides, when such a container iscarried between factories, the inside of the container is firstpreheated using a gas burner or the like, and then the molten materialis supplied into the container. The apparatus disclosed in JapanesePatent Laid-Open No. Hei 8-20826 has another problem that the stokeneeds to be removed together with a large lid for holding the stoke forpreheating because the stoke in the container is an obstacle during thepreheating, leading to a very low productivity.

In addition, a series of systems for supplying such molten aluminum hasa problem that the molten aluminum at a high temperature often comesinto contact with air, the aluminum is oxidized by ambient air. Suchslag (oxide) is a problem affecting the quality of the aluminum, and anoperator thus usually strains it out from the surface of the moltenaluminum in a tandish (container) through a sprue gate of the tandish.Therefore, improvements in productivity have been required, and, morethan that, the above straining work has sometimes been of little use forremoval of the oxide from the tandish.

The present invention is made to solve the above-described problems, andits object is to provide a technique of requiring no replacement ofparts such as a stoke and the like.

It is another object of the present invention to provide a techniquecapable of efficiently performing preheating.

It is still another object of the present invention to provide atechnique of eliminating the above-described work of removing oxide toimprove productivity.

To solve the above problems, a container of the present invention ischaracterized by comprising a sealed type container body capable ofstoring molten metal; a flow passage capable of flowing the moltenmetal, the passage is formed extended to an outside of the container,and the passage is formed towards an upper portion from an openingprovided at a position on an inner and near a bottom portion of thecontainer body; and means for controlling the pressure in the containerbody.

In the present invention, the flow passage for flowing the molten metalis configured to extend to the outer periphery of the container body andtoward the upper portion from the position on the inner and near thebottom portion of the container body. In other words, in the presentinvention, as compared to the apparatus disclosed in Japanese PatentLaid-Open No. Hei 8-20826, members such as the stoke and the like whichare exposed to the molten metal in the container become unnecessary,thus eliminating the necessity to replace the parts such as the stokeand the like. In addition, in the present invention, no member such asthe stoke which obstructs preheating is disposed in the container toimprove the productivity for preheating, thus enabling efficientpreheating.

Here, a method for supplying a molten metal using a container accordingto the present invention is characterized by comprising the steps of (a)reducing a pressure in a container so that the molten metal is loadedinto the container from outside of the container; and (b) supplying themolten metal from the container to the outside of the container. Here,the reducing a pressure in a container means that the pressure outsidethe container>the pressure inside the container. This state includes, inaddition to the case of reducing the pressure in the container, a caseof applying a pressure to the outside of the container, and further acase of reducing the pressure in the container and applying a pressureto the outside of the container.

The above-described loading of the molten metal into the containerutilizing the pressure difference between the inside and the outside ofthe container only requires that a furnace for supplying the moltenmetal is connected to the container through a member in the shape ofdrawing the molten metal into the container, for example, a pipe. Itbecomes unnecessary to connect the furnace for supplying the moltenmetal to the container through, for example, a tub member, so that thepossibilities of the molten metal coming into contact with air lessenremarkably, thus making it possible to decrease as much as possibleoxidation of the molten metal supplied into the container. Therefore, itbecomes possible to eliminate the work of removing oxide for improvedproductivity, and additionally to supply molten metal including littleor no oxide. Further, it is also possible to degas a gas component suchas hydrogen resolved in the molten metal. Such a gas component reducesproductivity in a die-casting step.

The step (b) is characterized by applying the positive pressure to thecontainer so that the molten metal is supplied from the container to theoutside of the container. For example, it is characterized that thecontainer having a first pipe connecting inside and the outside of thecontainer capable of flowing the molten metal, and the molten metal ispassing through the first pipe in the step (a) and step (b).

The applying the positive pressure to the container means that thepressure inside the container>the pressure outside the container. Thisstate includes, in addition to the case of applying the positivepressure to the container, a case of reducing the pressure outside ofthe container, and further a case of applying the positive pressure tothe container and reducing the pressure outside of the container.

In the present invention, the molten metal can be supplied from thefurnace for supplying the molten metal into the container and suppliedfrom the container to a server using, for example, the common firstpipe, so that the configuration can be very simplified. The presentinvention, however, also includes a case in which the molten metal isloaded and supplied through different pipes.

The method for supplying a molten metal of the present invention ischaracterized in that the container having a second pipe connecting theinside and the outside of the container, and the pressure in thecontainer is reduced and applied through the second pipe in the step (a)and step (b). The pressure in the container is reduced and appliedthrough the common pipe as described above enables the configuration ofthe container to be very simple.

Therefore, in the present invention, it becomes possible to load themolten metal into the container and supply the molten metal from thecontainer only by providing, for example, the first and the second pipefor the container. This makes it possible not only to simplify theconfiguration but also to decrease remarkably oxidation of the moltenmetal.

The method for supplying a molten metal of the present invention ischaracterized in that the step (a) further comprises, reducing apressure in the container so that the molten metal is loaded into thecontainer from the outside of the container; detecting a level of themolten metal; and controlling a pressure in the container according tothe detected level of the molten metal. This makes it possible to supplya proper amount of the molten metal into the container irrespective of,for example, the system configuration on the server side.

The method for supplying a molten metal of the present invention ischaracterized in that the step (a) further comprises the step of purginga space inside the container with a non-oxidizing gas after the moltenmetal is loaded. This makes it possible to further suppress oxidation ofthe molten metal supplied into the container.

The method for supplying a molten metal of the present invention ischaracterized in that the container having a first pipe connectinginside and the outside of the container capable of flowing the moltenmetal, and an effective inner diameter of the first pipe is about 65 mmto about 85 mm.

A system for supplying a molten metal of the present invention ischaracterized by comprising a container capable of storing the moltenmetal; a pipe capable of flowing the molten metal, and the first pipeconnecting inside and outside of the container; and an exhausting systemfor exhausting the inside of the container. Further, the system forsupplying a molten metal of the present invention is characterized bycomprising a container capable of storing the molten metal; a first pipecapable of flowing the molten metal, and the first pipe connectinginside and outside of the container; and a second pipe connecting theinside and the outside of the container, and the second pipe capable ofreducing a pressure inside of the container.

In the present invention, it is only required that a furnace forsupplying the molten metal is connected to the container through a pipefor drawing the molten metal into the container, so that thepossibilities of the molten metal coming into contact with air lessenremarkably, thus making it possible to decrease as much as possibleoxidation of the molten metal supplied into the container. Therefore, itbecomes possible to eliminate the work of removing oxide for improvedproductivity, and additionally to supply molten metal including littleor no oxide.

The system for supplying a molten metal of the present invention ischaracterized in that the effective inner diameter of the pipe forflowing the molten metal is about 65 mm to about 85 mm.

The system for supplying a molten metal of the present invention ischaracterized in that an inner opening of the pipe is formed at an innerlower portion of the container. Thereby, most of the molten metal to besupplied into the container through the pipe is supplied below thesurface of the molten metal which has already been supplied into thecontainer, that is, most of the molten metal to be supplied through thepipe is prevented from coming into contact with air in the containerduring the supply, so that oxidation of the molten metal can beeffectively prevented. Further, the opening of the pipe is disposed atsuch a position, thereby enabling supply of the molten metal from thecontainer to a server by application of a pressure through use of thepipe. In a container of a type of supplying the molten metal to theoutside by a differential pressure, when the pipe clogs, the moltenmetal in the container cannot be supplied, resulting in solidifiedmetal. The container of the present invention has an advantage that evenwhen the pipe attached to the container clogs because of somecircumstances, the molten metal can be supplied to the outside bydetaching this pipe and tilting the container like a teapot.

The system for supplying a molten metal of the present invention ischaracterized by further comprising means for detecting a level or aweight of the molten metal; and means for controlling the exhaustionsystem according to the detected level or weight of the molten metal.This enables supply of a proper amount of the molten metal into thecontainer. The means for detecting a level is characterized bycomprising a pair of electrodes which are provided on a ceiling portionof the inside of the container with a predetermined distancetherebetween, with tip portions thereof projecting at least to aposition of a maximum level in the container. The use of such means fordetecting a level enables detection of the level with a simpleconfiguration also in an environment at a high temperature causing themetal to melt. The means for detecting a level may be used togetherwith, for example, a weight sensor. For example, it is adoptable thatthe amount of the molten metal in the container is measured using theweight sensor in normal times, and the means for detecting a level withthe above-described configuration is used as means for detecting amaximum level for emergency. This enables construction of a safersystem.

A system for supplying a molten metal of the present invention ischaracterized by comprising loading a molten metal into the container byreducing a pressure in the container and transporting the container toat least a use point; and supplying the molten metal at the use point byapplying the positive pressure to the container. Here, the presentinvention is characterized in that the molten metal is, for example,aluminum, the container is transported to the use point through a publicroad, and molding procuct using the molten aluminum is performed at theuse point.

The present invention is a producing method for producing a moltenaluminum from a solid aluminum characterized by comprising the steps ofmelting the solid aluminum in a furnace; connecting the furnace and acontainer with a pipe; and reducing a pressure in the container so thatthe molten aluminum is loaded into the container through the pipe. Thisenables production of molten aluminum containing little oxide.

A producing method for producing an aluminum molding product produced bydie-casting of the present invention is characterized by comprising thesteps of melting an aluminum in a furnace; connecting the furnace and acontainer with a pipe; reducing a pressure in the container so that themolten aluminum is loaded into the container through the pipe; applyinga pressure to the container so that the molten aluminum is supplied intoa server through the pipe; and supplying the molten aluminum to analuminum die-casting machine to produce the aluminum molding product.This enables efficient production of a high quality aluminum moldingproduct with little oxide.

A producing method of an automobile of the present invention ischaracterized by comprising the steps of melting an aluminium in afurnace; connecting the furnace and a container with a pipe; reducing apressure in the container so that the molten aluminum is loaded into thecontainer through the pipe; applying a pressure to the container so thatthe molten aluminum is supplied into a server through the pipe; andsupplying the molten aluminum to an aluminum die-casting machine fromthe server to produce an engine for an automobile; and assembling theautomobile using the engine. This enables efficient production of anautomobile with a high quality engine with little oxide.

A system for supplying a molten metal of the present invention ischaracterized by comprising a container capable of supplying a moltenmetal by applying a positive pressure to the container; a liftingmechanism capable of holding the container, and raising and loweringwith holding the container; a transporting vehicle having a tank, andthe tank supplies a gas for applying the positive pressure to thecontainer.

A transporting vehicle of the present invention is characterized bycomprising a lifting mechanism capable of holding a container andraising and lowering with holding the container; a container capable ofsupplying a molten metal by applying a positive pressure to thecontainer.

According to the present invention, the tank for applying the positivepressure to the container is mounted on the transporting vehicle, andthe gas for applying the positive pressure is supplied from the tankinto the container capable of supplying a molten metal by applying apositive pressure to the container to feed the molten metal by thepressure with this gas, thus eliminating the necessity to tilt thecontainer as before. Therefore, for example, a rotation mechanism doesnot need to be provided on a fork lift truck, but only the liftingmechanism needs to be provided, resulting in a very simple mechanism. Inaddition, since the tank supplying a gas for applying the positivepressure is used as means for applying a pressure, for example,installation of a power generator which is considered as required when acompressor is mounted becomes unnecessary, leading to a reduction insize and weight. In a factory, replenishing gas is also very easy.

The aforementioned transporting device may be provided with means formeasuring (for example, a pressure gauge) provided at a fork portion ofa fork lift mechanism, for measuring the weight of the container, andmeans for controlling for controlling the supply of the gas from thetank supplying a gas for applying the positive pressure to the containerbased on the measurement result.

According to the configuration, when the weight of the container becomesequal to or less than a predetermined value, which indicates that apredetermined amount of the molten metal already supplied from thecontainer to the receiver side, the supply of the gas is stopped to stopthe supply of the molten metal. This enables a specified amount of themolten metal to be supplied without manpower but with a simpleconfiguration.

A supply apparatus of the present invention comprises a hermetic zonemeans for supplying metal into the hermetic zone; means for receivingthe supplied metal, in the hermetic zone; and means for controlling theoxygen concentration in the hermetic zone.

The supply apparatus of the present invention comprises a furnacecapable of holding and retaining heat in, or heating, the molten metal;a pipe for leading the molten metal into an hermetic chamber; means forcontrolling the oxygen concentration in the furnace and the hermeticchamber; and means for controlling the difference between the pressurein the furnace and the pressure in the hermetic chamber.

Further, the supply apparatus of the present invention comprises afurnace capable of holding and retaining heat in, or heating, the moltenmetal; a pipe for leading the molten metal into an hermetic chamber; andmeans for controlling the pressure in the furnace to be relativelyhigher than the pressure in the hermetic chamber to supply the moltenmetal to a use point. The supply apparatus may further comprise meansfor controlling the pressure in the furnace to be relatively lower thanthe pressure in the use point to return the molten metal into thefurnace.

The supply method of the present invention passes the molten metal inthe hermetice zone in which the oxygen concentration or the oxygenactivity is controlled.

A method for producing a metal product of the present inventioncomprises the steps of supplying a molten metal in an hermetic zone inwhich the oxygen concentration is controlled; and molding the suppliedmetal.

The control of the oxygen concentration or the oxygen activity isconducted so that oxidation of the metal is suppressed. The control ofthe oxygen concentration can be conducted not only by controlling theoxygen partial pressure but also by controlling the total pressure.Further, it is also adoptable to conduct control including temperature.Hereafter, a case only referring to the oxygen concentration shallinclude the concept of the oxygen activity. Depending on conditions oftemperature, pressure, oxygen concentration, and so on, not onlyoxidation of the metal is suppressed but also the metal is sometimesdeoxidized. In either case, the metal is supplied to the use point inthe hermetic zone while oxidation thereof being suppressed. The metal tobe supplied here includes, for example, metal in a melt or metal powder(including fine particles and ultra-fine particles, this applying to thefollowing). Further, as for the composition of the metal, either asingle element or an alloy can be used. As the means for controlling theoxygen concentration, there are, for example, an exhausting system and anon-oxidizing gas introduction system. These may be disposed incombination, or a plurality of systems may be provided. It is preferableto select, for use as the exhausting system, one or some in combination,as necessary, from among an exhaust blower and various types of vacuumpumps (for example, a rotary pump, a mechanical booster pump, aliquid-sealed pump such as a water-sealed pump, an oil diffusion pump, aturbo-molecular pump, an ion getter pump, a cryopump, and so on). Also avacuum gauge (vacuum meter) may be provided when necessary. Thenon-oxidizing gas can include rare gases, nitrogen, carbon monoxide,carbon dioxide, sulfur dioxide, sulfur hexafluoride, and so on. Fromamong these gases, one may be selected in accordance with the propertyof metal. The non-oxidizing gases may be used in combination.

The adoption of the above configuration enables supply of metal to theuse point in the hermetic zone with oxidation of the metal beingsuppressed in the supply apparatus of the present invention. Therefore,the generation amount of oxides such as oxide film, oxide and so on canbe suppressed to a very low level, thereby improving the productivity.

Besides, metals having low free energy of formation and a highreactivity such as magnesium, calcium, titanium, and so on have aproblem that they are susceptible to oxidation in processes of melting,holding, delivering, pouring, molding, and so on. The same goes in ametal in a state having excessive free energy on its surface such aspowder. These metals are not only susceptible to oxidation but also atrisk for ignition and explosion. According to the present invention,such metals can also be supplied in safety.

Besides, in the molding of metal, during supply of molten metal to adie-casting apparatus, the metal oxidizes and ignites to impair thestrength, accuracy, and appearance of a product. This is prominent inmetals susceptible to oxidation and hard to process, for example, amagnesium alloy and so on. One reason is that before a molten metal issupply to a cavity, oxide of the metal is contaminated thereinto.According to the present invention, the molten metal is supplied to thedie-casting apparatus with oxidation of the metal being suppressed,resulting in improved quality of products. This effect is more enhancedby controlling the oxygen activity in a flowing space of the moltenmetal including the cavity, as described later.

By the way, at the time of melting the above-described metal, forexample, a fireproof agent such as beryllium is sometimes added forfireproofing. Beryllium is well known as an element having a lowabundance of element as well as a very high toxicity. It is known thatberyllium adversely affects a human body, for example, a person has arespiratory disorder when he or she sucks its oxide. At present,beryllium diffuses in the environment during the producing step andthrough products containing it (pay attention to circumstances after theproducts turn into wastes). The use of such a harmful substance givesrise to a serious problem in viewpoints of safety of an operator andenvironment conservation. The present invention eliminates the necessityto use such a harmful fireproof gas, thus making it possible to ensurethe safety of the operator and prevent a harmful substance fromdiffusing in the environment.

Next, description will be made on the container of the presentinvention. Here, the container is applicable to both a case in which itis used in a fixed state (for example, a melting furnace, a storingfurnace, and so on of the molten metal) and a case in which it is usedin a movable state (for example, a container and so on).

A container of the present invention comprises a frame forming anhermetic zone; a heat insulation disposed inside the frame; and at leastone pipe disposed through the frame and the heat insulation.

Further, the present invention is a container capable of storing moltenmetal comprising means for applying a pressure to the furnace; and meansfor reducing the pressure in the furnace.

The frame forms a closed space being the hermetic zone therein. Further,the frame serves a function of holding the strength of the entirecontainer and a function of protecting the heat insulation from theoutside. The frame can be constituted of various kinds of metals, sothat a suitable material may be selected in accordance with the use ofthe container. This selection is preferably made in consideration ofphysical property and chemical property of contents to be stored in thecontainer. For example, the selection is made so that even if the heatinsulation is broken, the frame never melts or breaks due to the heat ofthe contents or a chemical reaction with the contents. This also appliesto the heat insulation, and various types of heat insulating bricks areselected in accordance with the use of the container.

The pipe provides an access between the outside of the frame and theinside space thereof. A plurality of the pipes may be provided. Forexample, an exhausting system is connected to this pipe to reduce thepressure in the space, thereby enabling control of the oxygenconcentration and the oxygen activity in the hermetic zone of being theinside. Besides, for example, a non-oxidizing gas introduction system isconnected to this pipe, thereby enabling supply of a non-oxidizing gasto the inside.

Furthermore, this pipe allows a fluid (molten metal or powder) to betaken out of/into the container by reducing and applying the pressure.For example, a case, in which the plurality of pipes are provided, isconsidered here. It is assumed that the contents are molten metal. Inthis case, when the non-oxidizing gas is introduced from the first pipeto apply a pressure to the hermetic zone, a force acts to push themolten metal to the outside through the second pipe. On the other hand,when the first pipe is connected to the exhausting system to reduce thepressure in the hermetic zone, the molten metal can be loaded from theoutside through the second pipe. The pipe is heated by a heater or thelike when necessary. The temperature is preferably set to be higher thanthe melting point of the contents flowing through the pipes. In thisevent, not only the movement of the molten metal or powder but also theoxygen concentration in the system can be controlled by the exhaustingsystem and the non-oxidizing gas supply system. As described above, theinvention of this application has one remarkable characteristic that thegeneration of pressure difference including the pressure reduced statecontributes both to the mass transfer of the molten metal or powder andthe prevention of oxidation. Besides, when the atmosphere in the pipebecomes oxidative, oxide attaches to the inside of the pipe to clog thepipe. In the present invention, it is possible not only to control theoxygen concentration in the pipe but also to prevent the contents fromremaining in the pipe, thus solving such a clogging problem.

Further, the container of the present invention also includes a formcomprising means for measuring the temperature in the hermetic zone andmeans for controlling the pressure in the frame in accordance with themeasured temperature.

A heat insulation such as a heat insulating brick or the like isdecreased in heat insulating performance with its aging. For example,when the molten metal is transported using a plurality of containers,the temperatures of the molten metal are sometimes different from othersdue to individual difference of the container. The temperature of themolten metal may sometimes drop to a level at which requirements of auser are not suitable. The container of the present invention employs aconfiguration in which the temperature of the hermetic zone or themolten metal is measured, and the pressure in the frame is controlledbased on the measured temperature. Such a configuration is employed tocontrol the heat conductivity in the system by the pressure. Thepressure in the frame of, for example, a container, in which atemperature drop of the molten metal is recognized during carriage, isreduced by the exhausting system, so as to suppress the heatconductivity of the inside to low. Thereby, the temperature of themolten metal can be kept irrespective of decrease in the heat insulatingperformance of the heat insulation. It is also possible to decrease thedifference in temperature between contents of a plurality of containers.Further, oxidation of the molten metal can also be prevented. Thepressure control can be conducted through use of not temperature itselfbut of a rate of change (for example, a differential value) intemperature, which configuration enables more accurate temperaturecontrol of the molten metal.

The present invention is a container capable of delivering molten metalcomprising a frame with a heat insulation on its inner face; a heaterdisposed on the inside of the heat insulation; means for measuring thetemperature of the molten metal; and means for controlling the heater inaccordance with the measured temperature.

The container of the present invention may have a configuration not onlyto control the pressure in the container in accordance with the measuredtemperature or the temperature change, but also a configuration tocontrol the temperature of the heater disposed in the container inaccordance with the measured temperature or the temperature change. Inthe configuration of the present invention, airtightness of the framecannot be a severe subject. The heater may have a configuration inwhich, for example, a resistor wire is exposed inside the heatinsulation. Other than that, it is also adoptable to use various type ofheaters such as, for example, a sheathed heater, a radiant tube, and thelike. The temperature in the container or the temperature or the changein temperature of the contents is measured to control the supply amountof energy (electric power, gas) to the heater in accordance with themeasurement value. Thereby, the temperature of the molten metal can bekept irrespective of decrease in the heat insulating performance of theheat insulation. It is also possible to decrease the difference intemperature between contents of a plurality of containers. Further, sucha configuration enables accurate management of the temperature of thecontents in the container. Moreover, the container of the presentinvention can also be configured in combination with the above-describedconfigurations of the respective containers of the present invention.

A molding apparatus of the present invention comprises means for moldingmetal supplied to a use point, an hermetic chamber disposed to surroundthe use point, and means for controlling the oxygen concentration in thehermetic chamber.

The molding apparatus of the present invention is applicable to varioustypes of molding apparatuses, for example, for injection molding ofmolding the molten metal supplied to the use point by pushing out itinto a space between a core mold (male mold) and a cavity mold (femalemold), compression molding, extrusion molding, blow molding, and so on.In the molding apparatus of the present invention, the metal to bemolded is supplied to the use point where the oxygen concentration iscontrolled (including reduction of the pressure). The metal can besupplied to the use point using the above-described supply apparatus andcontainer of the present invention. For example, in the conventionalmetal molding, the metal oxidizes and ignites during supply of the metalto the apparatus to impair the strength, accuracy, and appearance of aproduct. This is prominent in a metal susceptible to oxidation and hardto process, for example, a magnesium alloy. According to the presentinvention, the metal is supplied to the molding apparatus with oxidationof the metal being suppressed, resulting in improved quality of themolded product. In the case of a die-casting apparatus, the above effectis more enhanced by controlling the oxygen activity in a flowing spaceof the molten metal including a nozzle, a sprue, a runner, and a gate.For the enhancement, it is only required to provide a valve and anexhausting system or a non-oxidizing gas supply system on the oppositeside to the use point of the flowing space of the molten metal andcontrol the pressure difference relative to the use point and the oxygenconcentration.

A container according to another aspect of the present invention ischaracterized by comprising a sealed type container body capable ofstoring a molten metal, and the container has a through hole providedfor controlling a pressure in the container; and a refractory liningformed inside of the container, and the refractory lining has a passagecapable of flowing the molten metal, the passage is formed extended toan outside of the container, and the passage is formed towards an upperportion from an opening provided at a position on an inner and near abottom portion of the container body.

In the present invention, the flow passage of the molten metal isconfigured to be buried in a refractory lining having a high heatconductivity formed inside of the container so that the heat of thecontainer body easily conducts to the flow passage side. Therefore, whenmolten metal is stored in the container, the heat of the stored moltenmetal conducts through the refractory lining to make the flow passagealmost equal in temperature to the stored molten metal. In a viewpointof enhancing the heat retaining property of the container, the heatconductivity of the container is preferably as low as possible. In thepresent invention, the heat conductivity of a zone separating thecontainer body from the flow passage is made high with an intention.This prevents the molten metal flowing through the flow passage frombeing cooled by the flow passage to solidify and attach to the surfaceof the flow passage. In other words, when the molten metal graduallysolidifies and attaches to the flow passage, the flow passage(conventional pipe) becomes more likely to clog, but the presentinvention can effectively prevent clogging of the flow passage. Further,in the present invention, the flow passage becomes almost equal intemperature to the stored molten metal, which eliminates a decrease inviscosity of the molten metal flowing near the surface of the flowpassage, making it possible to supply the molten metal from thecontainer and load the molten metal into the container with a smallerpressure difference. In other words, the flow passage of the moltenmetal is constituted of the refractory lining having a high heatconductivity formed inside of the container, and the flow passage ismade almost equal in temperature to the stored molten metal, so that thecontainer of the present invention is very effective to a system ofloading and supplying the molten metal into/from the container utilizingthe pressure difference.

The container of the present invention is provided with a through holeused for controlling a pressure in the container, so that the moltenmetal can be loaded into the container though the flow passage byreducing the pressure in the container, for example, through the throughhole. In the present invention, the molten metal is loaded into thecontainer through the flow passage as described above, thereby allowingthe metal attached to the surface of the flow passage to be cleaned by ahotter molten metal flowing through the flow passage. Therefore, in thepresent invention, the provision of the through hole used forcontrolling a pressure in the container makes it possible to effectivelyprevent the flow passage from clogging.

In the present invention, the flow passage for flowing the molten metalis configured to extend to the outside of the container and towards theupper portion from the position on the inner and near the bottom portionof the container body. In other words, in the present invention, ascompared to the apparatus disclosed in Japanese Patent Laid-Open No. Hei8-20826, members such as the stoke and the like which are exposed to themolten metal in the container become unnecessary, thus eliminating thenecessity to replace the parts such as the stoke and the like. Inaddition, in the present invention, no member such as the stoke whichobstructs preheating is disposed in the container to improve theproductivity for preheating, thus enabling efficient preheating.

The container according to an embodiment of the present invention ischaracterized by further comprising a heat insulator inserted between aninner surface of the container body and the refractory lining(refractory member), and the heat insulator having a heat conductivitysmaller than that of the refractory lining. As the refractory lining, arefractory castable material can be used which has a large strength withrespect to, for example, molten aluminum. Besides, the heat insulationcan include, for example, heat insulating castable refractories andnon-castable heat insulating refractories (for example, board type heatinsulator). In any case, the heat insulation is set lower in density,heat conductivity, and so on than the refractory member. Note that it isadoptable to use the refractory member and the heat insulation in alayered structure.

In other words, in the container of the present invention, the heatconductivity between the container and the flow passage is intentionallyset to be higher than that between the inside and the outside of thecontainer. This suppresses temperature drop of the flow passage.Especially when the flow passage portion projects outward like thecontainer of the present invention, that region is likely to cool off.Hence, in the present invention, the heat conductivity is made lowwithin the portion separating the flow passage from the inside of thebody. This makes it possible to retain heat in the molten metal in thecontainer and additionally decrease cooling of the flow passage affectedby the outside, resulting in effective prevention of clogging of theflow passage. Moreover, if the flow passage can be kept at a hightemperature, the molten metal becomes low in viscosity, thus making itpossible to load and supply the molten metal into/from the containerwith a smaller pressure difference.

The container according to an embodiment of the present invention ischaracterized in that a bottom surface of the container body has aninclination towards the opening so that the opening is at a lowerposition of the body. Thereby, when the molten metal in the containerruns short, the substantial area of the refractory member in contactwith the molten metal in the container in the vicinity of the flowpassage becomes larger than the area at a place apart from the flowpassage. Therefore, it becomes possible to prevent as much as possiblethe flow passage from cooling to effectively prevent the flow passagefrom clogging, and load and supply the molten metal into/from thecontainer with a smaller pressure difference. In addition, feeding ofthe molten metal remaining in the container by tilting the container canbe efficiently performed with a reduced tilt angle and clogging of theflow passage being decreased as much as possible.

The container according to an embodiment of the present invention ischaracterized in that an upper portion of the container body is providedwith a hatch capable of opening and closing.

In the present invention, the provision of such a hatch makes itpossible that the hatch is opened and a heater such as a burner or thelike is inserted to preheat the container, for example, prior tointroduction of the molten metal into the container. Such preheatingwarms the flow passage through the refractory member, thereby making itpossible to prevent more effectively the flow passage from clogging, andload and supply the molten metal into/from the container with a smallerpressure difference. Since the flow passage can be previously warmed asdescribed above when the molten metal is loaded into the containerthrough the flow passage, the present invention is effectiveparticularly in that case.

The container according to an embodiment of the present invention ischaracterized in that the through hole is provided in the hatch.

The container is preheated by a gas burner prior to supply of the moltenmetal into the container as described above. This preheating isperformed by opening the hatch and inserting the gas burner into thecontainer. Therefore, the hatch is opened every supply of the moltenmetal into the container. In the present invention, such a hatch isprovided with a through hole for internal pressure control, so thatattachment of metal to the through hole for internal pressure controlcan be checked every supply of the molten metal into the container. Whenmetal attaches, for example, to the through hole, the metal only needsto be removed every occurrence. Therefore, the present invention enablesprevention of clogging of the pipe and hole used for internal pressurecontrol.

An apparatus for supplying a molten metal in still another aspect of thepresent invention is characterized by comprising a furnace for meltingthe metal and storing the molten metal, and the furnace has a supplysection for supplying the molten metal; a first pipe disposed on thesupply section, and an end portion of the first pipe is immersed in themolten metal; and a holding mechanism for elastically holding the firstpipe.

In the present invention, the end portion of the first pipe can beconnected to the second pipe provided, for example, at a container tosupply the molten metal from the furnace into the container through thefirst pipe and the second pipe. In this case, the molten metal can besupplied, for example, by generating a pressure difference between thecontainer side and the furnace side. More specifically, for example, byreducing the pressure in the container by a vacuum pump, the moltenmetal can be supplied from the furnace into the container through thefirst pipe and the second pipe. Thus, the present invention can lessenthe possibilities of the molten metal coming into contact with air toprevent oxidation of the molten metal. This eliminates the necessity ofthe work of removing oxide in which an operator strains the oxide outfrom the surface of the molten aluminum in the container through a spruegate of the container, enabling improved productivity. Further, in thepresent invention, since the first pipe connected to the second pipeprovided, for example, at the container is elastically held, thusgreatly facilitating, for example, the work of aligning the end portionof the first pipe to a port of the second pipe provided at thecontainer, enabling further improved productivity in combination withthe above-described function.

Therefore, a system for supplying a molten metal in a main aspect of thepresent invention is characterized by comprising a furnace for meltingthe metal and storing the molten metal, and the furnace has a supplysection for supplying the molten metal; a first pipe disposed on thesupply section, and an end portion of the first pipe is immersed in themolten metal; a holding mechanism for elastically holding the firstpipe; and a container having a second pipe capable of connecting to oneend of the first pipe, and the container is supplied with the moltenmetal through the first pipe and the second pipe, and characterized byfurther comprising means for reducing a pressure inside the container.

An embodiment of the present invention is characterized in that theholding mechanism holds the first pipe so that the other end portion ofthe first pipe is freely positioned. This makes it possible to alignmore smoothly the other end portion of the first pipe to the second pipeprovided, for example, at the container.

An embodiment of the present invention is characterized in that theholding mechanism comprises a pair of plate members facing with eachother at a predetermined distance, and each of the plate members has anopening at a predetermined position respectively, so that the first pipeis inserted therethrough; and an elastic member inserted between theplate members. Further, the embodiment of the present invention ischaracterized in that a diameter of each of the openings of the platemembers is sufficiently larger than an outer diameter of the first pipe,and the first pipe further comprises a holder provided on an outerperiphery of the first pipe, and an outer diameter of the holder islarger than the outer diameter of the first pipe. This allows theholding mechanism to be realized with a simple configuration.

An embodiment of the present invention is characterized by furthercomprising a joint mechanism for fastening the first pipe with a secondpipe to be connected to the first pipe. The provision of such a jointmechanism prevents displacement between the first pipe and the secondpipe after the alignment.

There is a well-known technology in which molding is performed usingmolten metal like aluminum die-casting. For this molding, it is requiredto prepare a molten aluminum alloy. There are several ways for preparingthe molten aluminum. In the first case, a melting furnace is providedfor every die-casting machine. In another possible case, aluminum ismolten in a centralized melting furnace, and die-casting machinesinclude respective storing furnaces. In a large-scale factory, thelatter may often be selected. Further, molten metal may be carried froma factory other than the die-casting factory.

The carriage of the molten metal from the centralized melting furnace toeach storing furnace and the carriage of the molten metal from the otherfactory are generally performed using a container such as a container orthe like. When the molten metal is supplied from the melting furnace tothe container, aluminum in a solid state is first molten in the meltingfurnace, and then the molten aluminum is tapped through a hole bored inthe melting furnace into a carrier container. On the other hand, supplyof the molten metal from the container to the storing furnace of thedie-casting machine, another melting furnace, or the like, is performedwith a container being tilted like tea is poured from a teapot.

The inventors propose a technique of supplying molten metal using apressure difference without tilting a container. This technique, throughuse of an airtight container including a pipe for loading and supplyingthe molten metal, reduces a pressure in the container to load the moltenmetal into the container and applies a pressure to the container tosupply the molten metal. Portions in direct contact with the moltenmetal such as the inner face of the container and the inner face of thepipe are lined with a refractory member and a heat insulation.

As describe above, the molten metal is sometimes supplied from themelting furnace or the storing furnace to the carrier container, andsometimes supplied from the container to the use point (for example, themelting furnace of the die-casting machine). In either case, as timerequired for the supply becomes shorter, the productivity is furtherimproved. On the other hand, as the flow rate of the molten metalbecomes higher, the degree of wear of the lining on the inner face ofthe pipe increases and the life of the pipe shortens.

The inventors have used a pipe about 50 mm in inner diameter at thebeginning. This is because of recognition that when the diameter isincreased, pressure feeding of the molten metal requires a highpressure. When the diameter of a pipe (sectional area of the pipe) isincreased, the weight of molten metal to be lifted increases, and inwhich viewpoint, a required pressure should increase. An increase in therequired pressure is disadvantageous. This is because leakage of thepressure spends long time to delay a stop action and a system forapplying a pressure becomes large. Especially when a tank for applying apressure is used to supply a compressed gas, as the pressure requiredfor the pressure feeding increases, the frequency of filling thecompressed gas to the tank increases.

However, when the inventors tested a pipe about 70 mm in inner diameterin developing process of a system for supplying a molten metal using apressure difference, it was found that aluminum can be supplied at apressure lower than the case using the pipe about 50 mm in innerdiameter. This indicates that the flow of aluminum in the pipe isaffected by its viscosity greater than expected in the case of the pipehaving a diameter of 50 mm. It shows that the effect of the viscositycoefficient and the like of aluminum is much greater in the pipe havinga diameter of 50 mm than in the pipe having a diameter of 70 mm,restricting the flow rate at a considerably high rate.

The flow rate of the molten metal flowing through the pipe is higher ata position closer to the center, and is the smallest at a position incontact with the inner face of the pipe. On the other hand, a too largeinner diameter of the pipe decreases the effect by the viscositycoefficient contributing to the entire flow but necessarily increasesthe pressure required to lift the molten metal. For example, in a pipeabout 100 mm in inner diameter, the pressure required for pressurefeeding is equal to or greater than that of the pipe about 50 mm ininner diameter. When the pressure is increased, the time required forrecovering the pressure is also long as described above, giving rise toa problem in safety.

In consideration of the inventors, Reynolds number is the greatest atthe center of the pipe and the smallest at a position in contact withthe inner face of the pipe. In the case of a smaller pipe diameter, mostpart of the flow in the pipe is restricted by the surface of the pipe.As the pipe diameter increases, the proportion of the portion restrictedby the pipe to the entire flow decreases. Within this region, as thepipe diameter is increased, the pressure required for pressure feedingdecreases. When the pipe diameter is further increased, the entire flowbecomes substantially steady. Consequently, it can be reasoned that theproportion of the portion restricted by the viscosity in the entire flowis small enough. Within this region, as the pipe diameter is increased,the pressure required for pressure feeding increases.

From the above fact, it is preferable, in the present invention, to setthe inner diameter of a pipe (including a flow passage) for transportingmolten aluminum by a pressure difference larger than 50 mm and smallerthan 100 mm. The inventors conducted tests with the inner diameter ofthe pipe being changed to about 50 mm, about 60 mm, about 65 mm, about70 mm, about 80 mm, about 90 mm, and about 100 mm. As a result, as theinner diameter was increased starting from about 50 mm, the pressure forpressure feeding decreased, but when the inner diameter exceeded about90 mm, a high pressure was required conversely. It was found thataluminum can be pressure fed at the lowest pressure in the case rangingfrom about 65 mm to about 80 mm in particular. On the other hand, it wasalso found that as the inner diameter becomes larger, the time requiredfor pressure feeding a predetermined amount (about 600 Kg) of moltenaluminum becomes shorter.

Conventionally, this type of pipe has been about 50 mm in innerdiameter. This is because it has been considered that in the case of apipe having a diameter larger than that, a high pressure is requiredwhen applying a pressure to a container to supply molten metal throughthe pipe. In contrast to this, the present inventors found that theinner diameter of a flow passage and a pipe linking thereto ispreferably about 65 mm to about 85 mm, greatly exceeding theabovementioned 50 mm, more preferably, about 65 mm to about 80 mm, andfurthermore preferably, about 70 mm. In other words, it can be reasonedthat when the molten metal flows upward through the flow passage and thepipe, two parameters such as the weight of the molten metal itselfexisting in the flow passage and the pipe and the viscosity resistanceof the inner wall of the flow passage and the pipe greatly affect aresistance which obstructs the flow of the molten metal. When the innerdiameter is smaller than 65 mm here, the molten metal flowing throughthe flow passage is affected by both the weight of the molten metalitself and the viscosity resistance of the inner wall at any position.When the inner diameter is 65 mm or larger, however, a zone hardlyaffected by the viscosity resistance of the inner wall graduallyincreases from near the center of the flow. This region has a very greateffect, so that the resistance obstructing the flow of the molten metalstarts decreasing. It is only required to apply a pressure to thecontainer at a very low pressure when supplying the molten metal fromthe container. In short, conventionally only the weight of the moltenmetal itself has been regarded as a variable factor of the resistanceobstructing the flow of the molten metal without taking the effect bysuch a region into consideration at all, and thus the inner diameter hasbeen set about 50 mm because of productivity, maintainability, and soon. On the other hand, when the inner diameter exceeds about 90 mm, theweight of the molten metal itself becomes very dominant as theresistance obstructing the flow of the molten metal, resulting inincreased resistance obstructing the flow of the molten metal. From theresult of a prototype container made by the present inventors, it isonly required to apply a pressure to the container at a very lowpressure for the case of an inner diameter from about 65 mm to about 80mm, and an inner diameter of about 70 mm is the most preferable inviewpoint of standardization and productivity. In other words, since thepipe diameter is standardized in a discrete manner, for producing, forexample, a pipe having an inner diameter of about 80 mm, it is requiredto use a structure and pipe one size greater than that for producing apipe having an inner diameter of about 70 mm. A smaller pipe diametercan be more preferable because of easy handling and good productivity.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram showing the configuration of a metalsupply system according to an embodiment of the present invention;

FIG. 2 is a diagram showing the relation between a container and astoring furnace according to the embodiment of the present invention;

FIG. 3 is a cross-sectional view of the container according to theembodiment of the present invention;

FIG. 4 is a plane view of FIG. 3;

FIG. 5 is a cross-sectional view of a part in FIG. 3;

FIG. 6 is a graph showing the relation between a pipe diameter and apressure of pressure feeding;

FIG. 7 is a view showing the configuration of a supply system from asecond furnace to a container in a second factory according to theembodiment of the present invention;

FIG. 8 is an enlarged side view of a holding mechanism and a connectingportion between a tip portion of a suction pipe and a tip portion of apipe in the container according to the embodiment of the presentinvention;

FIG. 9 is a plane view of the holding mechanism shown in FIG. 8;

FIGS. 10A to 10C are views for explaining actions of connecting the pipeof the container and the suction pipe of a supply furnace according tothe embodiment of the present invention;

FIG. 11 is a flowchart showing a producing method of an automobile usingthe system of the present invention;

FIG. 12 is a view schematically showing an example of a supply apparatusof the present invention;

FIG. 13 is a view schematically showing another example of the supplyapparatus of the present invention;

FIG. 14 is a view schematically showing an example of a melting furnaceof the present invention;

FIG. 15 is a view schematically showing an example of the configurationof the container of the present invention;

FIG. 16 is a view showing an example of a joint usable for connectingpipes;

FIG. 17 is a view schematically showing another example of theconfiguration of the container of the present invention;

FIG. 18 is a view schematically showing another example of theconfiguration of the container of the present invention; and

FIG. 19 is a diagram for explaining an example of a delivery model ofmetal using the supply apparatus and the container of the presentinvention.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described withreference to the drawings.

FIG. 1 is a diagram showing the entire configuration of a metal supplysystem according to an embodiment of the present invention.

As shown in the drawing, a first factory 10 and a second factory 20 areprovided at locations apart from each other across, for example, apublic road 30.

In the first factory 10, a plurality of die-casting machines 11 arearranged as use points. Each of the die-casting machines 11 moldsproducts in a desired shape by injection molding using molten aluminumas a raw material. The products can include, for example, parts relatingto an engine of an automobile and the like. Besides, the molten metal isnot limited only to an aluminum alloy, but alloys containing othermetals such as magnesium, titanium, and so on as main constituents arealso usable. Near the die-casting machines 11, there are storingfurnaces (local storing furnaces) 12 that temporarily store moltenaluminum before shots. This local storing furnace 12 is designed tostore the molten aluminum for a plurality of shots, so that the moltenaluminum is injected from the storing furnace 12 into the die-castingmachine 11 through a tandish (container) 13 or a pipe for every shot.Further, each of the storing furnaces 12 is provided with a level sensor(not shown) that detects the level of the molten aluminum stored in acontainer and a temperature sensor (not shown) that detects thetemperature of the molten aluminum. Detection results by these sensorsare passed to a control panel of each of the die-casting machines 11 ora central controller 16 in the first factory 10.

At a receiving station of the first factory 10, a receiving table 17 isdisposed for receiving a later-described container 100. The container100 received at the receiving table 17 in the receiving station isdelivered by a delivery vehicle 18 to a predetermined die-castingmachine 11, so that the molten aluminum is supplied from the container100 to the storing furnace 12. The container 100 after completion of thesupply is returned to the receiving table 17 in the receiving stationagain by the delivery vehicle 18.

In the first factory 10, a first furnace 19 is provided for meltingaluminum and supplying it to the container 100, and the container 100supplied with the molten aluminum from the first furnace 19 is alsodelivered by the delivery vehicle 18 to a predetermined die-castingmachine 11.

In the first factory 10, a display section 15 is disposed which states afact that the die-casting machines 11 demand for the additional aluminummelt. More specifically, for example, an ID number is given to everydie-casting machine 11 and displayed on the display section 15, so thatthe number on the display section 15 corresponding to the die-castingmachine 11 which demands for the additional molten aluminum is lightedup. Based on the display on the display section 15, an operator carriesthe container 100 to the die-casting machine 11 corresponding the numberusing the delivery vehicle 18 to supply the molten aluminum. The displayon the display section 15 is performed by a control of the centralcontroller 16 based on the detection result by the level sensor of thealuminum melt.

In the second factory 20, a second furnace 21 is provided for meltingaluminum and supplying it to the container 100. A plurality of types ofcontainers 100 are provided which are different, for example, incapacity, pipe length, height, width, and so on. For example, there area plurality of types of containers 100 different in capacity inaccordance with the capacities or the like of the local storing furnaces12 for the die-casting machines 11 in the first factory 10. However, itis, of course, adoptable to unify the containers 100 into one standard.

The containers 100 supplied with the molten aluminum from the secondfurnace 21 are mounted on a truck 32 for carriage by means of a forklift truck (not shown). The truck 32 carries the containers 100 throughthe public road 30 to near the receiving table 17 in the receivingstation in the first factory 10, so that the containers 100 are receivedat the receiving table 17 by means of a fork lift truck (not shown).Besides, vacant containers 100 placed in the receiving station arereturned to the second factory 20 by the truck 32.

In the second factory 20, a display section 22 is disposed which statesa fact that the die-casting machines 11 in the first factory 10 calladditional molten aluminum. The display section 22 is almost the same inconfiguration as the display section 15 in the first factory 10. Thedisplay on the display section 22 is performed by a control of thecentral controller 16 in the first factory 10, for example, via acommunication line 33. It should be noted that, out of the die-castingmachines 11 which demand for supply of the molten aluminum, thedie-casting machines 11, which are determined to be supplied with themolten aluminum from the first furnace 19 in the first factory 10, aredisplayed in distinction from the other die-casting machines 11 on thedisplay section 22 in the second factory 20. For example, it is designedto blink the numbers corresponding to the die-casting machines 11determined as above. This can prevent the molten aluminum from beingsupplied by mistake from the second factory 20 side to the die-castingmachines 11 which have been determined to be supplied with the moltenaluminum from the first furnace 19. Further, on this display section 22,data transmitted from the central controller 16 is also displayed inaddition to the above display.

Next, description will be made on the action of the metal supply systemconfigured as described above.

The central controller 16 monitors the amount of the molten aluminum ineach of the storing furnaces 12 through the level sensor provided ateach of the local storing furnaces 12. When there arises a demand forsupplying the molten aluminum to one storing furnace 12, the centralcontroller 16 transmits to the second factory 20 side through thecommunication line 33 the “ID number” of the storing furnace 12,“temperature data” of the storing furnace 12 detected by the temperaturesensor provided at the storing furnace 12, “form data” on the form(described later) of the storing furnace 12, final “time data” of thestoring furnace 12 running out of the molten aluminum, “traffic data” ofthe public road 30, “amount data” of the molten aluminum required forthe storing furnace 12, “temperature data”, and so on. In the secondfactory 20, these data are displayed on the display section 22. Based onthese displayed data, the operator determines on his or her experiencesthe point of time for dispatch of the container 100 from the secondfactory 20 and the temperature of the molten aluminum at the time of thedispatch so that the container 100 is delivered immediately to thestoring furnace 12 before the storing furnace 12 runs out of the moltenaluminum and the molten aluminum at that time is at a desiredtemperature. Alternatively, it is also adoptable to capture these dateinto a personal computer (not shown), estimate, through use ofpredetermined software, the point of time for dispatch of the container100 from the second factory 20 and the temperature of the moltenaluminum at the time of the dispatch so that the container 100 isdelivered immediately to the storing furnace 12 before the storingfurnace 12 runs out of the molten aluminum and the molten aluminum atthat time is at a desired temperature, and display the time andtemperature. Alternatively, it is also adoptable to automaticallycontrol the temperature of the second furnace 21 based on the estimatedtemperature. It is also adoptable to determine the amount of the moltenaluminum to be stored in the container 100 based on the aforementioned“amount data.”

When the truck 32 with the container 100 mounted thereon departs, passesthe public road 30, and arrives at the first factory 10, the container100 is received from the truck 32 at the receiving table 17 in thereceiving station.

Then, the received container 100 is delivered together with thereceiving table 17 to a predetermined die-casting machine 11 by thedelivery vehicle 18 so that the molten aluminum is supplied from thecontainer 100 to the storing furnace 12.

As shown in FIG. 2, this example is configured such that compressed airis sent out from a reservoir tank 101 into the hermetic type container100 to cause the molten aluminum stored in the container 100 to bedischarged through a pipe 56 and supplied to the storing furnace 12.Note that numeral 103 denotes a pressure valve, and numeral 104 denotesa leak valve in FIG. 2.

By the way, the storing furnaces 12 have various heights, and the tip ofthe pipe 56 is controllable to be placed at an optimal position abovethe storing furnace 12 by means of a lifting mechanism provided on thedelivery vehicle 18. The lifting mechanism, however, cannot cope byitself with the storing furnace 12 depending on its height in somecases. Hence, in this system, data regarding the height of the storingfurnace 12, the distance to the storing furnace 12, and so on arepreviously sent to the second factory 20 side as the “form data”regarding the form of the storing furnace 12, and on the second factory20 side, for example, the container 100 having an optimal form, forexample, an optimal height is selected and delivered based on the data.Note that the container 100 having an optimal size may be selected anddelivered in accordance with the amount to be supplied.

Next, the container 100 (container capable of supplying the molten metalby pressure) suitable for the system configured as described above willbe described with reference to FIG. 3 and FIG. 4. FIG. 3 is across-sectional view of the container 100, and FIG. 4 is a plane viewthereof.

The container 100 is configured such that a large lid 52 is provided atan upper opening 51 of a bottomed cylindrical body 50. Flanges 53 and 54are provided at outer peripheries of the body 50 and the large lid 51respectively, so that the flanges are fastened together with bolts 55 tofix the large lid 51 to the body 50. It should be noted that the outsideof the body 50 and the large lid 51 is made of, for example, metal andthe inside thereof is made of refractories, with a heat insulator beinginserted between the metal frame and the refractories.

At one point on the outer periphery of the body 50, a pipe attachmentportion 58 is provided which is provided with a flow passage 57 startingfrom the inside of the body 50 and communicating with the pipe 56.

Here, FIG. 5 is a cross-sectional view taken along a line A-A across thepipe attachment portion 58 shown in FIG. 3.

As shown in FIG. 5, the outside of the container 100 is constituted of ametal frame 100 a, and the inside thereof is constituted of a refractorymember 100 b, with a heat insulation 100 c in a plurality of layersbeing inserted between the frame 100 a and the refractory member 100 b.The heat insulation 100 c is formed here by lining, from the inner side,heat insulating castable refractries and a board type heat insulator.Besides, the flow passage 57 is formed to be sheathed in the refractorymember 100 b which is provided on the inside of the container 100.Further, to positively conduct heat in the container to the flow passageside, a region separating the inside of the container from the flowpassage is composed of the refractory member 100 b having a large heatconductivity. On the other hand, the heat insulating property on theoutside of the flow passage (opposite to the container body side) needsto be enhanced, and thus a heat insulation is disposed on the outside ofthe refractory member.

The flow passage 57 in the pipe attachment portion 58 extends toward anupper portion 57 b on the outer periphery of the body 50, through anopening 57 a provided at a position on the inner periphery of the body50 close to a bottom portion 50 a of the container body. The pipe 56 isfixed to communicate with the flow passage 57 in the pipe attachmentportion 58. The pipe 56 has the form of the letter Γ, so that an endportion 59 of the pipe 56 faces downward. More specifically, the endportion 59 of the pipe 56 is inclined, for example, at about 10° withrespect to the vertical line. Giving such an inclination reduces, forexample, splash of the molten metal from the molten metal surface to thecontainer side when the molten metal supplied from the end portion 59flows down to the local storing furnace side.

Feeding of the molten metal by the pressure may be performed with theend portion 59 of the pipe 56 sunk in the molten metal stored on thestoring furnace side. This decreasess the possibilities of the moltenmetal coming into contact with air and involving air during supply,thereby enabling improved quality of the molten metal.

The flow passage 57 and the pipe 56 linking thereto are preferablyalmost the same in inner diameter, about 65 mm to about 85 mm.Conventionally, this kind of pipe has been about 50 mm in innerdiameter. Here, FIG. 6 is a graph showing the relation between a pipediameter and a pressure for pressure feeding. This graph shows thedependence upon the pipe diameter of the minimum pressure required forpressure feeding when the weight of the molten metal in the container ischanged. As is clear from the drawing, it is found that a pressurerequired when the inner diameter of the pipe is about 50 mm and about100 mm is higher than that when the inner diameter of the pipe is withina range from about 65 mm and about 80 mm.

The pipe here is made by forming a ceramic layer on the inner surface ofSUS metal. The temperature of the molten aluminum was almost 700° C.

At almost the center of the aforementioned large lid 52, an opening 60is provided, and a hatch 62 with a handle 61 attached thereto isdisposed at the opening 60. The hatch 62 is provided with packing forsealing the inside of the container airtight, on a face on the large lid52 side. Packing made of silicon is circularly provided here. The hatch62 is provided at a position slightly higher than the upper face of thelarge lid 52. A portion on the outer periphery of the hatch 62 isattached to the large lid 52 through a hinge 63. This allows the hatch62 to freely open and close the opening 60 in the large lid 52. Inaddition, bolts with handles 64 for fixing the hatch 62 to the large lid52 are attached to two points of the outer periphery of the hatch 62 ina manner opposite to the position to which the hinge 63 is attached. Byclosing the opening 60 in the large lid 52 with the hatch 62 androtating the bolts with handles 64, the hatch 62 is fixed to the largelid 52. On the other hand, by inversely rotating the bolts with handles64 to release the fixation, the hatch 62 can be opened from the opening60 in the large lid 52. Then, with the hatch 62 opened, maintenance ofthe inside of the container 100 and insertion of a gas burner at thetime of preheating can be performed through the opening 60.

Further, a through hole 65 for internal pressure control for reducingand applying the pressure in the container 100 is provided at the centeror a position slightly off from the center of the hatch 62. To thethrough hole 65, a pipe 66 for applying and reducing the pressure isconnected. The pipe 66 extends upward from the through hole 65, bends ata predetermined height, and extends in the horizontal direction. Thesurface of a portion of the pipe 66 inserted into the through hole 65 isthreaded, and on the other hand, the through hole 65 is also threaded.This firmly screws the pipe 66 to the through hole 65.

To one end of the pipe 66, a pipe 67 for applying the pressure orreducing the pressure can be connected. A tank storing a compressed gasand a pump for applying the pressure are connected to the pipe forapplying the pressure, and a pump for reducing the pressure is connectedto the pipe for reducing the pressure. Then, it is possible to load themolten aluminum into the container 100 through the pipe 56 and the flowpassage 57 using a pressure difference resulting from reducing thepressure, and it is possible to pour the molten aluminum to the outsideof the container 100 through the flow passage 57 and the pipe 56 using apressure difference resulting from applying the pressure. It should benoted that use of an inert gas, for example, nitrogen gas as thecompressed gas makes it possible to prevent more effectively oxidationof the molten aluminum during the application of the pressure.

In the present invention, a connecting port of the pipe 67 for applyingor reducing the pressure is disposed not at the large lid but at thehatch so that an operator can check a clogging of the pipe 67 and theconnecting port. For example, clogging of the pipe 67 and the connectingport can be checked when necessary such as after carriage of thecontainer to a customer, before supply of molten metal by pressurefeeding, and so on. Therefore, the molten metal can be suppliedreliably.

In this embodiment, while the through hole 65 for applying and reducingthe pressure is provided in the hatch 62 which is disposed at almost thecenter portion of the large lid 52, the aforementioned pipe 66 extendsin the horizontal direction, thus making it possible to perform safelyand easily the work of connecting the pipe 67 for applying or reducingthe pressure to the pipe 66. Furthermore, the pipe 66 extends in thehorizontal direction as described above and thus can be rotated withrespect to the through hole 65 by a small force, so that the pipe 66screwed to the through hole 65 can be fixed and removed by a very smallforce, for example, without using a tool.

At a position slightly off from the center of the hatch 62 and oppositeto the abovementioned through hole 65 for applying and reducing thepressure, a through hole 68 for releasing pressure is provided, and arelief valve (not shown) can be attached to the through hole 68 forreleasing pressure. Thereby, for example, when the inside of thecontainer 100 reaches a predetermined pressure or higher, the inside ofthe container 100 is released to the atmospheric pressure in viewpointof safety.

In the large lid 52, two through holes 70 for level sensors are disposedwith a predetermined distance therebetween into which two electrodes 69are inserted respectively as the level sensors. The electrodes 69 areinserted into the through holes 70 respectively. The electrodes 69 aredisposed opposite to each other in the container 100, and their tipsextend, for example, to positions at a level almost the same as that ofa maximum level of the molten metal in the container 100. It is thuspossible to detect the maximum level of the molten metal in thecontainer 100 by monitoring the conduction state between the electrodes69, thereby enabling prevention of excessive supply of the molten metalto the container 100 with more reliability.

On the rear face of the bottom portion of the body 50, two channels 71having a cross section in a square shape into which, for example, a forkof the fork lift truck (not shown) is inserted and a predeterminedlength, are disposed, for example, in parallel to each other. Further,the entire bottom portion inside the body 50 is inclined to be low onthe flow passage 57 side. This reduces so-called remained melt when themolten aluminum is supplied to the outside through the flow passage 57and the pipe 56 by compression. In addition, when the container 100 istilted, for example, at the time of maintenance to pour the moltenaluminum to the outside through the flow passage 57 and the pipe 56, theangle of tilting the container 100 can be decreased, providing improvedsafety and productivity.

As described above, in the container 100 according to this embodiment,the through hole 65 for internal pressure controll is provided in thehatch 62, and the pipe 66 for internal pressure control is connected tothe through hole 65, so that attachment of metal to the through hole 65for internal pressure controll can be checked every supply of the moltenmetal into the container 100. This makes it possible to prevent cloggingof the pipe 66 and the through hole 65 used for controlling a pressurein the container.

Further, in the container 100 according to this embodiment, the throughhole 65 for internal pressure controll is provided in the hatch 62, andadditionally the hatch 62 is provided at almost the center of the upperface portion of the container 100 corresponding to a position of themolten aluminum where the level of the melt changes and melt dropssplash off at a relatively rare, resulting in less attachment of themolten aluminum to the pipe 66 and the through hole 65 used forcontrolling a pressure in the container. This makes it possible toprevent clogging of the pipe 66 and the through hole 65 used forcontrolling a pressure in the container.

Further, in the container 100 according to this embodiment, the hatch 62is provided in the upper face portion of the large lid 52, so that thedistance between the inner face of the hatch 62 and the liquid surfaceis longer by the thickness of the large lid 52 than the distance betweenthe inner face of the large lid 52 and the liquid surface. This reducesthe possibility of aluminum attaching to the inner face of the hatch 62provided with the through hole 65, making it possible to preventclogging of the pipe 66 and the through hole 65 used for controlling theinternal pressure.

Next, a supply system from the second furnace 21 to the container 100 inthe second factory 20 will be described with reference to FIG. 6.

As shown in FIG. 7, the second furnace 21 stores the molten aluminum.The second furnace 21 is provided with a supply section 21 a into whicha suction pipe 201 is inserted. The suction pipe 201 is disposed suchthat an end portion (another tip portion 201 b of the suction pipe 201)is immersed in the liquid surface of the molten aluminum in the supplysection 21 a. More specifically, one tip portion 201 a of the suctionpipe 201 extends close to the bottom portion of the second furnace 21,and the other tip portion 201 b of the suction pipe 201 is drawn outwardfrom the supply section 21 a. The suction pipe 201 is held basicallywith an inclination by means of a holding mechanism 202. The inclinationangle is, for example, about 10° with respect to the vertical line sothat the inclination matches that of the tip portion of the pipe 56 ofthe above-described container 100. The tip portion 201 b of the suctionpipe 201 is to be connected to the tip portion of the pipe 56 of thecontainer 100, and the matching of the inclinations thus facilitatesconnection between the tip portion 201 b of the suction pipe 201 and thetip portion of the pipe 56 of the container 100.

Then, the pipe 67 connected to a pump 313 for redusing the pressure isconnected to the pipe 66. Subsequently, the pump 313 is running forredusing the pressure in the container 100. This allows the moltenaluminum stored in the second furnace 21 to be loaded into the container100 through the suction pipe 201 and the pipe 56.

In this embodiment, in particular, the molten aluminum stored in thesecond furnace 21 is loaded into the container 100 through the suctionpipe 201 and the pipe 56, so that the molten aluminum never comes intocontact with outside air. Therefore, no oxide is generated, and as aresult, the molten aluminum supplied using this system is very excellentin quality. In addition, the work of removing oxide from the container100 also becomes unnecessary, resulting in improved productivity.

In this embodiment, in particular, introduction of the molten aluminuminto the container 100 and feeding of the molten aluminum from thecontainer 100 can be performed using substantially only two pipes 56 and312, thus enabling the system configuration to be very simple. Further,shapely decreased possibilities of the molten aluminum of coming intocontact with the outside air can almost eliminate generation of oxide.

FIG. 7 shows a producing flow of the above-described system when appliedto an automobile factory.

First, as shown in FIG. 6, the molten aluminum stored in the secondfurnace 21 is loaded (molten metal is received) into the container 100through the suction pipe 201 and the pipe 56 (Step 501).

Then, as shown in FIG. 1, the container 100 is carried by the truck 32through the public road 30 from the second factory 20 to the firstfactory 10 (Step 502).

Then, in the first factory (use point) 10, the container 100 isdelivered by the delivery vehicle 18 to the die-casting machine 11 forproducing an automobile engine, and the molten aluminum is supplied fromthe container 100 to the storing furnace 12 (Step 503).

Then, the die-casting machine 11 molds the automobile engine using themolten aluminum stored in the storing furnace 12 (Step 504).

At last, an automobile is assembled using the automobile engine thusmolded and other parts, resulting in a complete automobile (Step 505).

In this embodiment, the automobile engine is made of aluminum containinglittle or no oxide as described above, thus making it possible toproduce an automobile having an engine excellent in performance anddurability.

Next, another embodiment of the present invention will be described.

FIG. 12 is a view schematically showing an example of the configurationof a supply apparatus and a molding apparatus of the present invention.The following description will be made on an example in which thepresent invention is applied to molding of a magnesium alloy.

A storing furnace 420 is a furnace for storing metal in a melt (moltenmetal). As the material of a chamber 420 a of the storing furnace 420,18-8 stainless steel is used in this example, and further the insidethereof has been subjected to anodizing process with an FC plate. Thestoring furnace 420 stores a molten magnesium alloy 401 therein. Aheater 425 keeps the melting temperature in this storing furnace.Further, the storing furnace 420 is connected with an vacuum system 421that reduces the pressure the inside and a non-oxidizing gasintroduction system 422 that supplies a non-oxidizing gas. Numeral 422 bdenotes a reservoir of gas. In this example, the vacuum system 421includes at least one vacuum pump 421 b. Further, the non-oxidizing gasintroduction system 422 also serves a function of applying a pressure tothe inside of the storing furnace 420. Furthermore, the storing furnace420 includes a pressure gauge (G) 423 that measures the pressure thereinand a temperature sensor 424 that measures the temperature of the moltenmetal. As the pressure gauge 423, a Bourdon gauge, a Pirani gauge, a BAgauge, and the like are selectively used in accordance with the pressurerange in use. As the temperature sensor 424, a thermocouple, an emissionpyrometer, and the like can be used.

In a purge chamber 430, the molten metal is passed. The purge chamber430 is structured such that the inside can be kept airtight. Similarlyto the storing furnace 420, the purge chamber 430 is connected with avacuum system 431 that reduces the pressure the inside and anon-oxidizing gas introduction system 432 that supplies a non-oxidizinggas. In this example, the vacuum system 431 includes at least one vacuumpump 431 b. Further, the non-oxidizing gas introduction system 432 alsoserves a function of applying a pressure to the inside of the purgechamber 430. Numeral 432 b denotes a reservoir of gas. Furthermore, thepurge chamber 430 is also provided with a pressure gauge (G) 433 thatmeasures the pressure therein.

The storing furnace 420 and the purge chamber 430 are connected to eachother through a pipe 440 and a bypass pipe 442. Numeral 443 denotes abypass valve. A heater 441 such as a resistor or the like is woundaround the pipe 440. The heater 441 keeps the temperature inside thepipe at a temperature at which the magnesium alloy melts. Now, when thepressure in the purge chamber 430 is made lower than the pressure in thestoring furnace 420, the molten magnesium alloy 401 is pushed out fromthe storing furnace 420 through the pipe 440 to the purge chamber 430.On the other hand, when the pressure in the purge chamber 430 is madehigher than the pressure in the storing furnace 420, the moltenmagnesium alloy 401 remaining in the pipe is loaded from the purgechamber 430 side to the storing furnace 420. In either case, the oxygenconcentration in the system is controlled to suppress oxidation ofmetal. Thus, metal is safely supplied, without combustion or explosion,to a use point in the purge chamber 430. In addition, since oxidation ofmetal is suppressed, generation of oxide is also suppressed or nooxidation occurs. This makes it possible to supply high quality metalwith a clean surface and no oxide. Furthermore, in the presentinvention, since the oxygen concentration in the system is controlled tosuppress oxidation of metal, there is no need to add a fireproof agentsuch as hazardous beryllium. This also improves the work environment.Moreover, a harmful substance is never contained in products, remnants(such as burrs), and wastes (wastes and failures of products). This canprevent harmful substances from spreading into the environment.

By the way, the purge chamber 430 is also a supply point (use point) ofthe molten metal for a die-casting apparatus 450. In this example, aloading chamber 451 of the die-casting apparatus 450 is provided toproject into the purge chamber 430. The loading chamber 451 and thepurge chamber 430 are sealed airtight by welding or the like. Theloading chamber 451 has an opening through which molten metal (amagnesium alloy 1 in this case) is supplied. The supplied metal issupplied to a mold side by means of an injection cylinder 452.Incidentally, the loading chamber 451 is kept warm by heaters 453. Amold 454 a is a cavity mold and a mold 454 b is a core mold, and themetal supplied into a space therebetween is molded into a predeterminedshape. The molds 454 a and 454 b are intervened between clampingmechanisms 455 a (on the fixed side) and 455 b (on the moving side). Ahydraulic cylinder 457 can apply a pressure to the clamping mechanism455 b on the moving side.

According to the molding apparatus of the present invention, thesupplied metal is never oxidized at the use point. Therefore, no oxideis contaminated into products, resulting in high quality products.Further, the accuracy is also improved, and its effect is prominentparticularly in thin products. Moreover, products are improved inappearance without darkening.

Generally, oxide is generated as high as at 20% to 40% in the molding ofthe magnesium alloy, causing a very low productivity. According to thepresent invention, the generation of oxide can be suppressed to a verylow level. Therefore, according to the present invention, theproductivity can be improved to reduce the production cost.

Moreover, wastes discharged in the producing step and wastes generatedafter use of products contain hazardous beryllium and so on. Themagnesium alloy is also designated as a dangerous substance. Accordingto the present invention, the amount of wastes can be reduced and ahazardous substance is also unnecessary, thus enabling reduced cost oftreating the wastes. Moreover, use of the container of the presentinvention permits the magnesium alloy as a dangerous substance to becarried in safety.

FIG. 13 is a view schematically showing another example of the supplyapparatus of the present invention. Description will be made here on theconfiguration in which a melting furnace 410 is provided at a priorstage of the storing furnace 420 shown in FIG. 10.

FIG. 10 is a view schematically showing an example of the meltingfurnace of the present invention. The melting furnace 410 is a furnacefor melting metal in a solid state. The configuration of the meltingfurnace 410 is very similar to that of the storing furnace 420. As thematerial of a chamber 410 a of the melting furnace 410, 18-8 stainlesssteel is used in this example, and further the inside thereof has beensubjected to anodizing process with an FC plate. A molten magnesiumalloy 401 is thrown into the melting furnace 410 and heated by a heater415. Numeral 416 denotes a partition wall. Further, the melting furnace410 is connected with a vacuum system 411 that reduces the pressure theinside and a non-oxidizing gas introduction system 412 that supplies anon-oxidizing gas. Numeral 412 b denotes a reservoir of gas. In thisexample, the vacuum system 411 includes at least one vacuum pump 411 b.Further, the non-oxidizing gas introduction system 412 also serves afunction of applying a pressure to the inside of the melting furnace410. Furthermore, the melting furnace 410 includes a pressure gauge (G)413 that measures the pressure therein and a temperature sensor 414 thatmeasures the temperature of molten metal.

For throwing a solid metal 401 b into the melting furnace 410, anairtight door 463 is first opened, and the solid metal 401 b is loadedinto a purge chamber 461 from the outside. The airtight door 463 isclosed, and the inside of the purge chamber 461 is exhausted by anexhausting system 466. With a bypass 467 being opened to balance thepressures in the purge chamber 461 and a throw-in chamber 462, theairtight door 464 and a heat insulating door 465 are opened. The solidmetal is moved by a pusher or a drawer. A bottom portion of the throw-inchamber 462 has a rotation mechanism whose rotation throws the solidmetal into the melting furnace 410.

FIG. 15 is a view schematically showing an example of the configurationof a container of the present invention. This container (container) 470comprises a frame 471 forming an hermetic zone being literally hermetic,a heat insulation 472 disposed on the inside of the frame 471, and pipes473 and 474 disposed through the frame 471 and the heat insulation 472.Further, a temperature sensor 475 is also provided for measuring thetemperature in the hermetic zone

The frame 471 forms a closed space that is the hermetic zone therein.Further, the frame 471 serves a function of holding the strength of theentire container 470 and a function of protecting the heat insulation472 from the outside. The frame 471 can be constituted of various kindsof metals, and thus a suitable material may be selected in accordancewith use of the container. This selection is preferably conducted inconsideration of physical property and chemical property of contents tobe stored in the container. For example, the selection is conducted sothat even if the heat insulation is broken, the frame never melts orbreaks due to the heat of the contents or a chemical reaction with thecontents. This also applies to the heat insulation, and thus varioustypes of heat insulating bricks are selected in accordance with use ofthe container.

The pipes 473 and 474 provide an access between the outside of thecontainer 470 and the inside space thereof. One or a plurality of suchpipes may be provided. For example, a not-shown exhausting system isconnected to this pipe 473 to reduce the pressure inside the container,thereby enabling control of the oxygen concentration and the oxygenactivity in the hermetic zone of the inside. Besides, for example, anon-oxidizing gas introduction system is connected to this pipe 473,thereby enabling supply of a non-oxidizing gas to the inside.

The above-describe application and reduction of a pressure allows afluid (molten metal or powder) to be taken into/out of the container.When the non-oxidizing gas is introduced through the pipe 473 to apply apressure to the hermetic zone, the molten metal can be pushed to theoutside through the pipe 474. On the other hand, when the pipe 473 isconnected to the exhausting system to reduce the pressure in thehermetic zone, the molten metal can be loaded from the outside throughthe pipe 474. The pipe 474 is heated by a heater or the like whennecessary. The temperature is preferably set to be higher than themelting point of the contents flowing through the pipe. In this event,not only the movement of the molten metal or powder but also the oxygenconcentration in the system can be controlled by the exhausting systemand the non-oxidizing gas supply system. As described above, the presentinvention has one remarkable characteristic that the generation ofpressure difference including the pressure reduced state contributesboth to the mass transfer of the molten metal or powder and theprevention of oxidation. Besides, when the atmosphere in the pipe 474becomes oxidative, oxide attaches to the inside of the pipe to clog thepipe. In the present invention, it is possible not only to control theoxygen concentration in the pipe 474 but also to prevent the contentsfrom remaining in the pipe, thus solving such a clogging problem.

FIG. 16 is a view showing an example of a joint usable for connectingpipes. The container of the present invention can serve a functionsubstantially equivalent to that of the storing furnace 420 in theabove-described embodiment. In other words, it is possible to use one ora plurality of containers 470 in place of the storing furnace 420. Inthis case, a pipe 474 only needs to be connected to a pipe 440 on theside to which metal is supplied (for example, the purge chamber 430).

The pipe 474 and the pipe 440 can be connected to each other using, forexample, a joint 475. The joint 475 includes gaskets 476 and is thusairtightly connected with the pipe 474 and the pipe 440. When thegaskets 476 are made of a resin, it is preferable to cool theneighborhood of the gaskets by water-cooled heads 477. The water-cooledheads 477 can be omitted when using gaskets made of copper, gold or thelike. In addition, this joint 475 can also be used to connect the pipe473 to the exhausting system and the gas introduction system.

FIG. 17 is a view schematically showing another example of theconfiguration of the container according to the present invention. Inthis container 480, a frame 471 has an opening that is sealed airtightwith a lid 471 b. Further, this container 480 is connected to anexhausting system 476 through a pipe 473.

In addition, there provided is a controller 477 that measures thetemperature of a molten metal 401 using a temperature sensor 475 andcontrols the exhausting system 476 in accordance with the measuredtemperature or the rate of change in temperature. For example, openingand closing of a valve 476 b is controlled by the controller 477. Theadoption of the above-described configuration enables control of theheat conductivity in the system by pressure in the container of thepresent invention.

A heat insulating member such as an insulating fire brick or the like isdecreased in heat insulating performance with its aging. For example,when molten metal is transported using a plurality of containers, thetemperatures of the molten metal are sometimes different from others dueto individual difference of the container. The temperature of the moltenmetal may sometimes drop to a level at which requirements of a user arenot suitable. As for the container of the present invention, it ispossible to reduce the pressuree by the exhausting system the inside ofthe frame of, for example, a container in which a temperature drop ofthe molten metal is recognized during carriage, so as to suppress theheat conductivity of the inside to low. Thereby, the temperature of themolten metal can be kept irrespective of decrease in the heat insulatingperformance of the heat insulation. It is also possible to decrease thedifference in temperature between the contents of the plurality ofcontainers. Further, oxidation of the molten metal can also beprevented. The pressure control can be conducted through use of nottemperature itself but of a rate of change (for example, a differentialvalue) in temperature, which configuration enables more accuratetemperature control of the molten metal.

FIG. 18 is a view schematically showing another example of theconfiguration of the container according to the present invention. Thiscontainer 490 comprises a frame 471 and a lid 471 b with a heatinsulation 472 on their inner faces, a heater 491 disposed on the insideof the heat insulation 472, a temperature sensor 475 that measures thetemperature of a molten metal 401, and a controller 492 that controlsthe heater 475 in accordance with the measured temperature or the rateof change in temperature. For example, the temperature of the metal 401is appropriately managed by controlling a power supply 493 that supplieselectric power to the heater 491 in accordance with the rate of changein the temperature measured by the temperature sensor 475. In thisembodiment, airtightness of the container is not expected from aviewpoint of temperature management. It is of course preferable tocontrol the pressure and the oxygen concentration of the inside. Thisshould be conducted particularly when unstable metal is stored.

This example shows an appearance of the container 490 which is mountedon a loading platform of a truck or a ship. An electrode 495 is exposedon the loading platform 494 to ensure an electrical connection with anelectrode 496 on the container side when the container is placed at apredetermined position. Numeral 497 denotes an insulating member such asan insulator. In this case, the power supply 493 can be mounted on thetruck. Alternatively, it is also adoptable to share it with batteries ofthe truck. The adoption of such a configuration enables delivery andsupply of high quality metal.

FIG. 15 is a diagram for explaining an example of a delivery model ofmetal using the supply apparatus and container of the present invention.

For example, in the case of using molten metal, there are aboutconceivable three aspects. The first one is a case in which the meltingfurnace or the storing furnace is provided near a use point, a factorywith the molding apparatus, or the like. The second one is a case inwhich a small-size melting furnace is provided for every moldingapparatus. The third one is a case in which metal is molten at apredetermined place and the molten metal is delivered to a use point.The present invention is applicable to any of the cases and providesimproved quality, improved safety, improved productivity, and reducedenergy cost. The aforementioned second case is conceivable as the mostdisadvantageous in a viewpoint of energy. In this case, it is onlyrequired to dispose near the use point the storing furnace 420 of thepresent invention or the container 470, 480, or 490 of the presentinvention, for example, as shown in FIG. 11. The metal is kept in a goodstate and delivered in safety. The above-described configurationconsiderably reduces the energy cost. Further, the configuration alsoeliminates the cost of the melting furnaces individually disposed at usepoints and the cost of installation space thereof.

INDUSTRIAL AVAILABILITY

As has been described, the present invention can provide a containerrequiring no replacement of parts such as a stoke and the like. Further,the present invention makes it possible to eliminate the work ofremoving oxide and so on to improve productivity. Furthermore, thepresent invention makes it possible to supply molten metal by applyingthe pressure or to load molten metal by reducing the pressure in thecontainer. Moreover, the duration for supplying the molten metal can beshortened. In addition, the time required to stop supply of the moltenmetal can be shortened, resulting in improved safety.

1. A molten metal supply container which is capable of being loaded on afork of a forklift including a tank for storing a compressed gas andcapable of being transported by the forklift, comprising: a containerwhich is capable of storing a molten metal and includes a first openingportion on an upper portion thereof; a flow path which is communicatedwith inside/outside of the container and through which the molten metalis capable of being flowed; a lid which is disposed to cover the firstopening portion and includes a second opening portion approximately at acenter thereof, the second opening portion having a smaller diameterthan the first opening portion; a hatch which is provided on an uppersurface portion of the lid to be openable/closable and is provided witha passage through which the compressed gas for increasing pressure inthe container is supplied from the tank into the container, the passagebeing communicated with the inside/outside of the container; and a pairof channel members which is provided to a bottom portion of thecontainer and to/from which the fork is capable of beinginserted/withdrawn.
 2. A molten metal supply container according toclaim 1, further comprising: a pipe connecting the passage and extendsto an upper direction from the upper portion of the container and bendsand extends to a horizontal direction at a predetermined height.
 3. Amolten metal supply container according to claim 1, wherein the pipe isdetachably screwed into the passage.
 4. A molten metal supply containeraccording to claim 1, wherein the passage is approximately at a centerof the hatch.